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Internet of Things laboratory project infrastructure

There are various possibilities on how to create an MQTT broker. It may be implemented as PC software (Linux, Windows-based, virtual or physical machine), however naturally we're looking for IoT device, capable of hosting MQTT broker. Here comes a solution based on Raspberry Pi (or clones).
Note, we're going to install Mosquitto MQTT broker.

We assume, your RPi installation is installed, updated and the network interface is up, connected to the local or Internet, and there is no firewall.

Installing an MQTT broker on Raspberry Pi contains some tricks regarding current Armbian OS distribution.

The instruction below applies to Raspian version Stretch, on Raspberry Pi 3 B. The original Armbian distribution comes with outdated Mosquitto libraries. Depending on the current state of updating the distro, it may be necessary to remove any *mosquitto* repositories before continuing this instruction. Please refer to the // /etc/apt/sources.list.d/ // folder and find any currently installed mosquitto packages:

cd /etc/apt/sources.list.d/
ls *mosquitto*

In case above code returns any source, remove it:

rm <here comes the name>.list

Next follow the steps below to install Mosquitto for Stretch:

cd ~/Downloads
wget http://repo.mosquitto.org/debian/mosquitto-repo.gpg.key
sudo apt-key add mosquitto-repo.gpg.key
cd /etc/apt/sources.list.d/
sudo wget http://repo.mosquitto.org/debian/mosquitto-stretch.list
sudo apt-get update

cd ~/Downloads
wget http://security.debian.org/debian-security/pool/updates/main/o/openssl/libssl1.0.0_1.0.1t-1+deb8u6_armhf.deb
sudo dpkg -i libssl1.0.0_1.0.1t-1+deb8u6_armhf.deb
wget http://ftp.nz.debian.org/debian/pool/main/libw/libwebsockets/libwebsockets3_1.2.2-1_armhf.deb
sudo dpkg -i libwebsockets3_1.2.2-1_armhf.deb
sudo apt-get install mosquitto mosquitto-clients

Once the installation is finished test, if mosquitto works:

mosquitto

The server should start, present network configuration and also print messages on client connection (if any):

The Mosquitto server runs in the foreground now and its log is redirected to the console. It runs without any configuration loaded. You can connect to it anyway, for testing purposes. Any MQTT client (including installed command-line ones should work). Refer to the section below on MQTT client.

To kill server use Ctrl+C.

Once Mosquitto server is in the public network, virtually anyone can connect to it as a client. This is not desired state thus it is essential to provide some security.

To enable credentials there is a need to configure /etc/mosquitto/mosquitto.conf file, along with providing a link to the file containing users and passwords (password_file /etc/mosquitto/pwfile) and to disable anonymous access (allow_anonymous false):

listener 1883
persistence true
persistence_location /var/lib/mosquitto/
persistence_file mosquitto.db
log_dest syslog
log_dest stdout
log_dest topic
log_type error
log_type warning
log_type notice
log_type information
connection_messages true
log_timestamp true
allow_anonymous false
password_file /etc/mosquitto/pwfile

To create a hashed password file use mosquitto_passwd. Sample command adding an user named iot and providing it a password is presented below:

sudo mosquitto_passwd -c /etc/mosquitto/pwfile iot

Enter password for user iot twice.

To append next user to the existing file, omit -c in the command above.

Now it is time to make mosquitto server start automatically on Raspbian boot. Unfortunately, modern Mosquittos' installer (here version 1.4.12) provides incompatible settings for autostart in case of Raspbian Stretch. You need to configure service yourself. While it may sound bad, it is not so difficult indeed.
Time to create a new service, through configuration file for Mosquitto. File is: /etc/systemd/system/mosquitto.service . Note - if this file exists, that perhaps means your installation package correctly handled new autostart mechanisms, thus Mosquitto may be already enabled to autostart. To check if your mosquitto is already starting automatically, reboot the system, then check if your Mosquitto is listening:

sudo reboot

and once your RPi restarts, re-connect terminal and issue:

netstat -l -p |grep 1883

Your RPi should answer something like this:

If you see the server ready and listening, do not follow this manual - it is in case your server does not start automatically on boot-up.

First remove old configuration (if any):

sudo update-rc.d mosquitto remove

next, create new /etc/systemd/system/mosquitto.service file:

sudo nano /etc/systemd/system/mosquitto.service

and fill it with following content:

[Unit]
Description=Mosquitto MQTT Broker daemon
ConditionPathExists=/etc/mosquitto/mosquitto.conf
Requires=network.target

[Service]
Type=simple
ExecStart=/usr/sbin/mosquitto -c /etc/mosquitto/mosquitto.conf -d
ExecReload=/bin/kill -HUP $MAINPID
PIDFile=/run/mosquitto.pid
Restart=on-failure

[Install]
WantedBy=multi-user.target

Note - the configuration file for Mosquitto server is located in /etc/mosquitto/mosquitto.conf (default, as configured in /etc/systemd/system/mosquitto.service file) and the service, while working, inserts a process identifier (PID) into the file: /run/mosquitto.pid (defaults, reconfigurable in /etc/mosquitto/mosquitto.conf).

Now enable the service and reboot to test it working:

sudo systemctl enable mosquitto.service
sudo reboot

There are various MQTT clients. One of the most convenient yet offering full features and great GUI and also the one that does not require any installation is Java-based MQTT-SPY. Simply download it, and run.

Once the main screen appears, please add new connection:

Next provide connection details (currently your MQTT server does not need any credentials, it simply accepts anonymous connections from anyone):

Give it some name, client ID and IP address of your RPi (if you're running on the same machine, use 127.0.0.1 - IP loopback).

Now click [Open connection]. MQTT-Spy may ask you to save the connection. This may fail if you run MQTT-Spy client for the first time - you need to create default configuration file first. Nevertheless you should see the following window with green coloured tab (if succesfully connected):

In case connection fails, first check if both (client and server) can connect on port 1883 and validate IP addresses.

Now it is time to test MQTT messages forwarding.
We will simulate it using one client both for publishing and subscribe.
First, it is time to subscribe. Click New tab in the “Subscriptions and received messages” section then enter topis you want to subscribe to then click [Subscribe]. Assuming you're the only one using the server, you may subscribe to all communicates using wildcard # (hash), as below:

Once done, click yellow # tab to observe incoming communicates.
Next step is to publish any topic to … yourself (actually that sounds odd, anyway remember it is for testing purposes - in a real environment it is rare Published and Subscriber of the particular topic are the same system). To publish an MQTT message, write in the “Publish Message” section sample Topic and Payload and click [Publish]:

Right afterward, you should see the forwarded message through the MQTT broker to appear in the “Subscriptions and received messages” section, presenting Topic and Payload you entered during sending, as below:

Programming (flashing) ESP8266 01 dongle.

There are 2 versions of the ESP01 (ESP-01 / ESP9266 01) dongle: 512kB and 1MB (8Mbit) If you have 512kB version, do not even think about programming it - most of the firmware available is already for at least 1MB flash size.If your memory is bigger, then you need to adjust addresses where appropriate section of the flash memory starts (see Flash Memory Map, note it is not the same as Memory Map).

The code below shows some flashing scenarios (Ubuntu 17.10 x64, python 2.7).
Erase contents:

pczekalski@s317-pc01:~$ sudo ~/.local/lib/python2.7/site-packages/esptool.py --chip esp8266 --port /dev/ttyUSB0 erase_flash

Flash original firmware (Esprif):

pczekalski@s317-pc01:~$ pczekalski@s317-pc01:~$ sudo ~/.local/lib/python2.7/site-packages/esptool.py --chip esp8266 --port /dev/ttyUSB0 write_flash --flash_freq 20m --flash_size detect --flash_mode dio 0x0000 ~/Downloads/ESP8266_NONOS_SDK-2.1.0/bin/boot_v1.7.bin 0x01000 ~/Downloads/ESP8266_NONOS_SDK-2.1.0/bin/at/512+512/user1.1024.new.2.bin 0x3FC000 ~/Downloads/ESP8266_NONOS_SDK-2.1.0/bin/esp_init_data_default.bin 0x7e000 ~/Downloads/ESP8266_NONOS_SDK-2.1.0/bin/blank.bin 0x3fe000 ~/Downloads/ESP8266_NONOS_SDK-2.1.0/bin/blank.bin

Write firmware for router:

sudo ~/.local/lib/python2.7/site-packages/esptool.py --chip esp8266 --port /dev/ttyUSB0 write_flash --flash_freq 20m --flash_size detect --flash_mode dio 0x0000 ~/Documents/Git/esp_wifi_repeater/firmware/0x00000.bin 0x10000 ~/Documents/Git/esp_wifi_repeater/firmware/0x10000.bin

Live stream is available at:

rtsp://IP:554/user=admin&password=password&channel=1&stream=0.sdp?real_straeam--rtp-caching=100

Only Internet Explorer works. Camera requires external converter from the stream above, to the http-based one, i.e. Motion server.

Stream parameters are:

#smartmetering Create a network-enabled system that monitors high voltage and current for the home system.
Hardware is ESP32 with WiFi connection. It should display it locally on the OLED display (an integrated ESP32 board) and should report it to the MQTT server.
Configuration should enable following features:

• Individual identification of the devices via some identifier in the flash memory.
• Remote configuration via AP and via connected wireless interface:
  • At the beginning system should expose access point.
  • Once configured and successfully connected to the infrastructure, management interface should be available via the infrastructure address.
  • If device cannot connect to the infrastructure, it should present the AP again (timeout to be provided)
• There should be a button to reset configuration and provide clean startup
• Configuration should provide MQTT client config (MQTT server address, credentials if any and message string and period).
• Summary power consumption should be present and stored in persistent memory periodically (to be adjusted)

#sensornetwork\\
A sensor network (temperature / humidity DHT22) of the ESP8266-01 devices, battery operated, identifiable, constituting a mesh network. Each device shall have reporting capability. The system should also consist of middleware (MQTT + NodeRED + database + web server) to store history and present data to the end user over the web (as a whole network, not a separate device). Note - those devices are to be battery powered thus power usage optimisation is a must!

#smarthouse\\
An interface for our office coffee machine to switch it on and off remotely via relays. Level monitoring of the Coffee (possibly optical) is also very welcome. An interface should send notifications to the users, i.e. via social media.

#teaching #education\\
A module with a network interface (possibly ESP32 or WeMOS D1 R2 or WeMOS Mini D1) providing digital outputs that you can individually set or reset via a WEB interface. Web Access via infrastructure or directly via AP (configuration of the infrastructure via AP).

#networking\\
A solution for a gateway collecting sensor data through WiFi and forwarding it for a long distance connection over LoRA networks.

#environment\\
Battery operated mobile device presenting dust level PM2.5 and PM10 (possibly others, sensor dependent), with networking capability. The PMS sensors are to be used in this project (requires porting of the existing library from C# to the chosen language.

#environment\\
A sensor device for PM2.5 and PM10 (based on existing PMS sensor) with the capability to forward the measurements, store and present them in the cloud solution.